1. Field of the Invention
The present invention is directed generally to an electromagnetic relay, and more particularly to a relay including a coil, a core arranged axially in the coil, a first yoke formed as an armature having one leg forming a working air gap relative to the first end of the coil and the armature being coupled to a contact spring. The relay also includes a second yoke that is L-shaped, the second yoke having a first leg facing toward a second end of the core and having a second leg extending essentially parallel to the axis of the coil where the free end of the first yoke is seated in the region of a free end of the second leg of the second yoke. The relay also includes a tension restoring spring which acts on an extension of the first and second yoke and which extends essentially parallel to the axis of the coil.
2. Description of the Related Art
A relay structure of the type described above is shown, for example, in German Patent No. 32 32 679, although such relay structures are also known in many other embodiments. Relays of this type can be manufactured relatively simply and at a relatively low cost. They are rugged when subject to external influences and are, therefore, used in great numbers. One such use is in motor vehicles.
Relays of the known type having this traditional design each comprise a plate-shaped armature which is usually seated at the yoke in the region of an end edge. Although other embodiments are also known having an angled armature, the bearing location even in such angled armatures is normally situated roughly in extension of the pole surface. When high DC currents are switched with such relays, there is a great amount of material which migrates from the contacts and there is also a relatively great tendency for the contacts to weld. These undesired effects are especially pronounced when the melted contact material, which is a result of the arc across the contacts can solidify at the same location as the arc, such as when there is no relative motion at the contact locations. This is frequently the case with relays of the type described above since the contact springs are usually directly connected to the armature.
A further disadvantage of the traditional relay arrangement is that the force exerted on the armature by the restoring spring may also have to generate the quiescent contact force which opposes the excitation force. Such opposing forces are present even when the armature is being attracted in these traditional systems. Care must, therefore, be exercised to see that the magnet system, which includes the coil, is designed so that the force generated by the excitation system at every point in time of the response is greater than the opposing forces exerted by the restoring spring and potentially also by the contact springs. When the difference between the force curves of these two opposing forces is excessively low, there is a risk that the relay will not entirely pull through or will not pull through quickly enough to provide reliable electrical contact, particularly given unfavorable tolerance conditions.